Modern day telecommunications networks are a web of a variety of nodes for delivering information from sender to recipient. In traditional public switched telephone networks (PSTNs), these nodes are circuit switched connections for relaying information along presumably secure, well-established routes. A relatively new phenomenon in telecommunications is the emergence of packet data networks. Transmission routes in packet data networks are dynamic and allow flexibility in information flow so that data is transmitted along paths most efficient for delivery. Indeed, the hallmark of the packet data network is its method of routing which ensures greater bandwidth for delivery of information.
An issue associated with all telecommunications transmissions, but more pronounced in packet data networks (due to the unpredictable nature of packet transmission routes), is the security of the node through which the information passes. This is because unauthorized interception of transmission is possible at many points along a route using relatively unsophisticated equipment. In some applications, such as military or corporate communications, a secure transmission is essential. With the increasing convergence of packet data and circuit switched networks, the likelihood of transmitting information via a network node which is subject to interception is significant. Therefore, traditional assumptions about the security of telecommunications networks, or the nodes contained therein, are no longer warranted.